Endophytes of native grasses from South-America. Biodiversity and ecology

IANNONE L.J

Lexington Kentucky, USA

Congreso; Joint Meeting of the Mycological Society of America; 2010

American Society of Mycology

 Whereas the symbiosis between asexual epichloë-endophytes and agronomic grasses is considered to be mutualistic, few is known about these symbiosis in wild grasses.  In Argentina, these endophytes have been detected in 37 native grass species. Although sexual stages have not been found in South-America, morphological characterization and phylogenetic analyses have revealed the existence of a high diversity of hybrid endophytes in this country, where grasses harboring endophytes have been found in all kind of environments from tropical forest to cold deserts. Whereas some endophytes seem to be strictly associated to one host species in a particular environment, Neotyphodium tembladerae presents an extremely wide environmental and host range from USA to Argentina.  In those host species, inhabiting different environments, the incidence of endophytes is highly variable among populations and in most of the cases is clearly associated with environmental conditions. Although endophytes can be easily lost at seed level, some host like Bromus auleticus, an excellent forage grass, present a very high endophyte incidence. In this host, the high fungal incidence could be explained by the beneficial effects conferred by the endophyte, as enhanced growth and resistance to pathogen fungi. Preliminary analyses indicate that some endophytes could produce lolines but are unable to produce lolitrem B or ergot alkaloids. These results suggest the existence of a diversity of endophytes that could not be detected with the markers used up to now and that many of these grasses and their endophytes could be used in forage breeding programs. Although our knowledge on endophytes of native grasses is increasing, more research is needed in order to understand the role of the endophytes in other native hosts, as well as their diversity in different countries from South-America. This knowledge will allow us to understanding the origin and evolutionary strategies of asexual endophytes.